A DEVELOPED SOLAR COMBINATION UNIT FOR COOKING AND WATER DESALINATION

Improving the double slope solar still performance by using flat-plate solar collector and cooling glass cover

Performance investigation of a new designed vacuum flat plate solar water collector: A comparative theoretical study

Performance enhancement of flat-plate and parabolic trough solar collector using nanofluid for water heating application

This paper reviews the impacts of employing inserts, nanofluids, and their combinations on the thermal performance of flat plate solar collectors. The present work outlines the new studies on this specific kind of solar collector. In particular, the influential factors upon operation of flat plate solar collectors with nanofluids are investigated. These include the type of nanoparticle, kind of base fluid, volume fraction of nanoparticles, and thermal efficiency. According to the reports, most of the employed nanofluids in the flat plate solar collectors include Al2O3, CuO, and TiO2. Moreover, 62.34%, 16.88%, and 11.26% of the utilized nanofluids have volume fractions between 0 and 0.5%, 0.5 and 1%, and 1 and 2%, respectively. The twisted tape is the most widely employed of various inserts, with a share of about one-third. Furthermore, the highest achieved flat plate solar collectors’ thermal efficiency with turbulator is about 86.5%. The review is closed with a discussion about the recent analyses on the simultaneous use of nanofluids and various inserts in flat plate solar collectors. According to the review of works containing nanofluid and turbulator, it has been determined that the maximum efficiency of about 84.85% can be obtained from a flat plate solar collector. It has also been observed that very few works have been done on the combination of two methods of employing nanofluid and turbulator in the flat plate solar collector, and more detailed work can still be done, using more diverse nanofluids (both single and hybrid types) and turbulators with more efficient geometries.

Performance investigation on solar thermal conversion of a conical cavity receiver employing a beam-down solar tower concentrator

The thermal output of the flat-plate solar water collector (FPSWC) is lower owing to higher heat loss and poor heat removal by the heat transfer fluid. Converting a laminar into a turbulent flow does not require a significant investment than other methods which need to study further for higher thermal output. In this work, the contribution of perforated and plain tube inserts to improving the thermal output of FPSWC is studied and compared with plain riser tubes at 0.0167 kg/s. The perforation provided along the tube insert improved the fluid mixing between hot and cold fluid zones and enhanced the heat transfer coefficient (HTC). Further, the tube inserts act as extended heat surfaces by their frictional contact at the top and bottom inside the riser tube. The collector’s maximum and average instantaneous thermal efficiencies are 78.4 and 57.7% with a perforated insert, where the average thermal efficiency is 40 and 15.9% higher than using a collector with plain riser tubes and with plain tube inserts. The exergy efficiencies of the collector with perforated tube insert, plain tube insert, and without inserts are 3.9%, 3.3%, and 2.5%, respectively. The average exergy efficiency of a perforated inserted absorber is 31.25 and 90.9% higher than the collector with plain tube inserts and without the insert. The convective HTC has reached a maximum of 5.79 W/m2 K for the perforated insert, which is higher than the other two collectors.KeywordsSolar collectorHeat transferEnergy efficiencyFlow insertHeat transfer coefficient

Effects of utilizing nanofluid as working fluid in a lab-scale designed FPSC to improve thermal absorption and efficiency

Solar energy is the best alternative to limited fossil fuels. The foremost important means of utilizing solar energy are solar collectors. The most common types of solar collectors are flat plate solar collectors. A great deal of theoretical research has been conducted to enhance the flat plate solar collector efficiency. One effective way to increase the efficiency is by using an improved thermal properties fluid as nanofluid. In this paper, a numerical study has been made to enhance the efficiency and improve the performance of solar collector via the use of (Multi-Wall Carbon Nano Tube-water) MWCNT-H2O nanofluid instead of traditional fluid like water as working fluid under the weather of Mosul city / Iraq (36.3489° N, 43.1577° E). One dimensional dynamic model using implicit finite difference method was used. Solving energy conservation equations through the various layers of the solar system is the basis upon which the current model was based. Effects of nanoparticle volume fraction and mass flow rate on the working fluid stream temperature differences, and the thermal efficiency were studied. The mass flow rate was varied from 0.004 kg/s to 0.03 kg/s, while the volume fraction was varied from 0% to 6%. The results of "Nanofluid Based Flat Plate Solar Collector" were compared with the experimental results presented by [1]. The comparison established a good match between the current results and experimental results. The results showed an increase in the working fluid outlet and inlet temperature difference and collector thermal efficiency due to the addition of MWCNT nanoparticles. The temperature difference of "Nanofluid Based Flat Plate Solar Collector" was found 28.8⁰C at 0.014 kg/s and 6% in April, while it was 25 ⁰C at the same condition in the "Water Based Flat Plate Solar Collector case". Also, the thermal efficiency of "Nanofluid Based Flat Plate Solar Collector" was found 2.41% to 6.68% more than the "Water Based Flat Plate Solar Collector case".

Enhancement techniques can be applied to flat-plate liquid solar collectors towards more compact and efficient designs. For the typical operating mass flow rates in flat-plate solar collectors, the most suitable technique is inserted devices. Based on previous studies from the authors, wire coils were selected for enhancing heat transfer. This type of inserted device provides better results in laminar, transitional and low turbulence fluid flow regimes. To test the enhanced solar collector and compare with a standard one, an experimental side-by-side solar collector test bed was designed and constructed. The testing set up was fully designed following the requirements of EN12975-2 and allow us to accomplish performance tests under the same operating conditions (mass flow rate, inlet fluid temperature and weather conditions). This work presents the thermal efficiency curves of a commercial and an enhanced solar collector, for the standardized mass flow rate per unit of absorber area of 0.02 kg/sm2 (in useful engineering units 144 kg/h for water as working fluid and 2 m2 flat-plate solar collector of absorber area). The enhanced collector was modified inserting spiral wire coils of dimensionless pitch p/D = 1 and wire-diameter e/D = 0.0717. The friction factor per tube has been computed from the overall pressure drop tests across the solar collectors. The thermal efficiency curves of both solar collectors, a standard and an enhanced collector, are presented. The enhanced solar collector increases the thermal efficiency by 15%. To account for the overall enhancement a modified performance evaluation criterion (R3m) is proposed. The maximum value encountered reaches 1.105 which represents an increase in useful power of 10.5% for the same pumping power consumption.

Chapter 236 - The Solar Cooker HS 5521 and HS 5921 Tested in Indonesia

The conventional solar still (CSS) unit faces challenges such as low productivity (Pd) and thermal efficiency (ηth) due to the limited temperature difference between the hot water and the cold interior glass cover surfaces (ΔTw-gi). This study addresses these issues by introducing enhancements in the CSS unit, incorporating a v-corrugated-type basin, internal reflecting mirror, flat-plate solar collector (FPSC) still, and FPSC nanofluids. A v-corrugated-type basin, internal reflecting mirror, FPSC still, and FPSC nanofluids elicited a significant improvement in the distillate productivity (Pd) up to approximately 22.39%, 41.72%, 70.10%, and 104.13% compared to the CSS unit. This increase in the Pd is attributed mainly to a notable raise in the ΔTw-gi, showing increments of around 34.33%, 52.32%, 77.37%, and 112.87% compared to the CSS unit. Moreover, a v-corrugated basin, internal reflecting mirror, FPSC still, and FPSC nanofluids substantially increased the average daily thermal efficiency (ηth), around 22.01%, 26.71%, 39.57%, and 56.21%, respectively. The results confirmed that integrating the v-corrugated basin, internal reflecting mirror, FPSC still, and FPSC nanofluids within a combined seawater distillation system can significantly enhance the performance of the CSS unit. These different combinations effectively raised the basin water temperature (Tw) and ΔTw-gi, consequently improving the overall performance of the solar still unit.

This study experimentally investigated the performance characteristics of water and MWCNT/Fe3O4 binary nanofluid as a working fluid in a flat plate and vacuum tube solar collectors. As a result, the highest efficiency was 80.3% when 0.005 vol.% MWCNT/0.01 vol.% Fe3O4 binary nanofluid was applied to the flat plate solar collector, which was a 17.6% increase in efficiency, compared to that when water was used. In the case of the vacuum tube solar collector, the highest efficiency was 79.8%, which was 24.9% higher than when water was applied. Besides, when the mass flux of MWCNT/Fe3O4 binary nanofluid was changed from 420 to 598 kg/s·m2, the maximum efficiencies of the flat plate and vacuum tube solar collectors were increased by 7.8% and 8.3%, respectively. When the MWCNT/Fe3O4 binary nanofluid was applied to the vacuum tube solar collector, the efficiency improvement was much more significant, and the high performance could be maintained for wide operating conditions, compared with the flat plate solar collector.

A comprehensive review on solar cooker with sun tracking system

Small sized absorber in a flat plate solar collector is beneficial in terms of cost and minimum heat losses. However, its detailed thermal performance compared to standard size collector is still not fully understood. There is a paucity of research to appreciate thermal performance of solar water heating collector with consideration of a small absorber size (below 1m2) and a standard absorber size (2 m2). The present study attempts to investigate the energy and exergy efficiencies of flat plate solar water heating collector with two absorber plate areas (2 m2 and 0.74 m2) to enumerate size of the absorber required for improved first and second law thermal efficiencies of the collector. The efficiencies of these two collector designs are experimentally compared with the help of a test facility available in the site for given operating temperatures and rate of flow. The combined experimental uncertainty due to the measuring instruments and the measured parameters is also ascertained. The obtained results highlight the significance of the larger absorber size (2m2) for higher thermal efficiency, and lower absorber size (0.74m2) for higher exergetic efficiency. The highest thermal efficiency obtained is 77.38% for larger absorber size, and the highest exergy efficiency of 13.21% is obtained for lower absorber size collector. It is demonstrated that larger and lower absorber size of the collector have higher thermal efficiency and higher exergy efficiency, respectively, than some of the published works.

در تحقیق حاضر، برای تأمین حرارت مورد نیاز گلخانه، یک سامانه ی گرمایش خورشیدی مجهز به متمرکزکننده ی سهموی خطی و جمع کننده ی خورشیدی تخت دو منظوره، پیشنهاد گردید. در این سامانه از یک مخزن برای ذخیره حرارت تولید شده استفاده شد. جریان سیال حامل حرارت در داخل متمرکزکننده به‌صورت اجباری و با استفاده از پمپ انجام گرفت. یک جمع کننده ی خورشیدی در داخل گلخانه نصب گردید که در طول روز، وظیفه گردآوری تابش خورشید و ذخیره حرارت در مخزن و در شب نقش مبدل حرارتی برای انتقال حرارت ذخیره شده در سامانه ی گرمایش، به محیط گلخانه را داشت. ارزیابی سامانه ی پیشنهادی در سه سطح دبی سیال عبوری در متمرکزکننده (0/44، 0/75 و 1/5 لیتر بر دقیقه) و دو حالت با و بدون استفاده از جمع کننده ی تخت خورشیدی انجام گرفت. نتایج تحقیق نشان داد که بیشترین بازده متمرکزکننده در بالاترین دبی سیال عبوری حدود 71 درصد به‌دست آمد. با بالا بردن دبی از 0/44 تا 1/5 لیتر بر دقیقه، به‌طور متوسط ذخیره حرارت در مخزن 32/14 درصد بهبود داشت. با استفاده از جمع کننده ی تخت خورشیدی، به طور متوسط 26/67 درصد و با بالا بردن دبی تا 1/5 لیتر بر دقیقه، 30 درصد در مصرف برق گرم کن کمکی، صرفه جویی گردید. در نهایت، بالاترین مقدار سهم خورشیدی سامانه پیشنهاد شده در تحقیق حاضر، 66 درصد بود که در بیشترین دبی سیال عبوری و با استفاده از جمع‌کننده‌ی تخت خورشیدی مشاهده شد.